Chemical Engineering Interview Questions on Industrial Catalysis which asked in companies listed below [GATE Material]
  • PDIL
  • EIL
  • BARC
  • GAIL
  • IOCL
  • ONGC
  • HPCL
  • DRDO
  • DAE
  • HWB
  • NPCL
  • ISRO
  • RCF
  • HCL
  • BPCL
  • HZL
  • SAIL
  • NTPC
  • FCI
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Fluid Mechanics and Transport Process Chemical Engineering Interview Questions 

1.            An ideal fluid is an incompressible and __________ fluid.
2.            For a Newtonian fluid shear stress is directly proportional to __________
3.            Kinematic viscosity of a liquid is dynamic viscosity divided by its __________
4.            In M, L, T system of dimension, Power is represented as __________
5.            Weber number is ratio of inertial force to __________ force.
6.            For incompressible fluid, continuity equation in integral form is Q = __________
7.            In flow net equipotential lines are orthogonal with __________
8.            Relative roughness of a pipe surface is its absolute roughness divided by its __________
9.            In laminar flow through pipe as Reynolds number increases the friction coefficient __________
10.         Pitot - static tube measures __________ pressure.
11.         Turbulent velocity fluctuations in a flow are measured by __________ meter
12.         For a solid sphere falling under gravity at terminal settling velocity in a fluid the buoyant force is equal to __________
13.         Pressure drag on a body is due to the formation of __________
14.         Ergun's equation relates __________
15.         Reciprocating pumps are suitable for high pressure rise and __________ discharge
16.         An example of Positive displacement pump is __________
17.         In a centrifugal pump as head increases discharge __________
18.         Power required by a fan is proportional to the discharge, pressure rise and __________
19.         Pump suitable for corrosive liquid is __________

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20.         Fans have __________ pressure rise than blowers.
21.         The unit of specific weight of a fluid in SI system is ______________
22.         One centipoise is equal to ______________ Pa-s
23.         The pressure inside a soap bubble will be ______________ than the surrounding atmospheric pressure
24.         Give an example of non-Newtonian fluid ______________
25.         The unit of one standard atmospheric pressure is 101.32 ______________
26.         Gauge pressure is absolute pressure ______________ atmospheric
27.         Pressure Dynamic similarity is similarity of ______________
28.         In M, L, T system dimension of angular velocity is ______________
29.         The density of manometric fluid used in an inverted manometer should be ______________ than the density of flowing fluid
30.         For steady incompressible fluid flow, the continuity equation is ______________
31.         For flow over flat plate, the critical Reynolds number is ______________
32.         Reynolds number is the ratio of inertial force and ______________ force.
33.         Mach number is the ratio of ______________ to ______________
34.         Cd of an orifice is always ______________ than Cc
35.         The suppressed sharp crested weir is 0.6 m high and discharges water at a head of 1.2 m. The coefficient of discharge of the weir is ______________
36.         The gas flow velocity through a fluidized bed should be less than or equal to ______________ velocity
37.         Give an example of rotary pump ______________
38.         Blowers are suitable for ______________ discharge than compressors
39.         Mass and weight of a body are differentiated in terms of the ____________ acting on it
40.         Viscosity may be described as the ratio between ____________ and ____________

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41.         Paint is ____________ by nature
42.         Torricelli's equation is stated as ____________
43.         Pressure of a liquid can be converted into the ____________ of the liquid by dividing by the corresponding density
44.         Water is not a ____________ liquid
45.         The compressible fluid used in an inverted manometer is ____________
46.         The unit for Poise is ____________
47.         An ideal fluid has no ____________ or ____________
48.         The length required to establish fully developed flow in the entire cross section of the pipe is called ____________
49.         The skin friction drag may be expressed by the equation F/?.
50.         For scaling up laboratory data to an industrial scale, the three similarities are ____________ ____________ and ____________
51.         Froude number is expressed as a ratio between ____________ and ____________ forces
52.         A pitot tube is used to measure ____________ velocities in a pipe line
53.         The forces acting on an aeroplane flying at a constant speed at a given altitude are ____________, ____________ and ____________
54.         The forces acting on a particle in a batch fluidized bed at steady state are ____________ ____________ and ____________
55.         Ergun's equation is useful in predicting the ____________ in a packed column
56.         In a centrifugal pump, water enters at the ____________ of the impeller
57.         Viscous liquids are transported by a ____________ pump
58.         The equilibrium position of the float in a rotameter is determined by the balance of     three forces. These are ___________, ___________ and ___________
59.         For an orifice meter, the pressure recovery is ________ than that for a venturi meter
60.         Dynamic pressure is the difference between ________ and ________

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61.         Pump size is determined on the basis of __________and_____________
62.         The velocity gradient, beyond the boundary layer is equal to _________
63.         The coefficient of discharge for a given orifice is a function of ___________and ___________
64.         Inclined manometer is used for ____________
65.         Pressure drop is __________ in globe valve as compared to gate valve

Short Notes - Fluid Mechanics Questions

1.            Inclined manometer.
2.            Flow of fluid in Boundary layer.
3.            Boundary layer separation.
4.            'Hydraulically smooth' pipes.
5.            Expansion and contraction losses.
6.            Equivalent length of fittings.
7.            Flow in non-circular conduits.
8.            Pneumatic transport.
9.            One seventh power law states ?
10.         Give any two examples of Non-Newtonian fluid.
11.         Define the term "Bulk Modulus".
12.         State Newton's Law of viscosity.
13.         State the value of specific weight of mercury in kN/m3.
14.         State any three dimensionless number related to fluid flow and explain their significance
15.         Explain the term "Geometric similarity" and "Kinematic similarity
16.         Explain the following terms (i) Vapor pressure and (ii) Bulk modulus
17.         State the Pascal's law of pressure at a point
18.         What are the desirable properties of manometric fluid?
19.         Distinguish between Laminar and Turbulent flow with example
20.         Distinguish between subsonic flow and supersonic flow

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21.         Explain the term "Boundary Layer" and friction drag
22.         Discuss the mechanism of fluidization
23.         Give some industrial applications of fluidization
24.         What are the applications of diaphragm pump?
25.         Define "stream tube"
26.         Write the differential form of continuity equation for two-dimensional steady flow of incompressible fluid.
27.         What is "Drag Coefficient".
28.         Write the expression for head loss due to sudden expansion.
29.         Define the term "relative roughness" in flow through rough pipes.
30.         What is "hydraulic mean radius"?
31.         What is the optimum included angle of the divergent section of a venturi meter?
32.         Define the term "Stagnation pressure".
33.         State any two types of weirs used for flow measurement.
34.         Name any two metal wires used in Hot wire anemometer.
35.         For what application magnetic flow meter is needed?
36.         What factors govern the "pressure drop" in fluidized bed?
37.         Define the term "Design Point" of a pump.
38.         What is "Critical fluidization velocity"?
39.         What is the theoretical maximum suction lift of a centrifugal pump?
40.         Name any three rotary type positive displacement pumps.

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41.          Differentiate between compressible and incompressible fluids.
42.         What is kinematic viscosity? Write its unit.
43.         Write the physical significance of Reynolds number.
44.         What is the relationship between the drag coefficient and Reynolds number in the Stoke's law range (Reynolds number < 1)?
45.         Write the principle of orifice meter.
46.         What is the head loss of the fluid at the entrance of a straight pipe?
47.         Explain 'Cavitation' in pumps.
48.         Define 'Minimum fluidization velocity'.
49.         Define 'Equivalent diameter' for fluid flow through channels of non-circular cross section.
50.         Write the principle of Magnetic flow meter.
51.         Write continuity equation for three dimensional motion of an incompressible fluid.
52.         Give two industrial applications of packed beds.
53.         Write Bernoulli's equation. State its assumptions.
54.         Differentiate between reciprocating and centrifugal pumps.
55.         Explain the principle of hot wire anemometer.
56.         Define 'Volumetric efficiency' of the positive displacement pump.
57.         Define NPSH in centrifugal pumps.
58.         What are the two types of fluidization?
59.         Write the Hagen Poiseuille's equation for laminar flow in Newtonian fluid.
60.         Define: a) Form drag b) Skin drag c) Boundary layer                                                      d) Compressible flow e) Smooth and rough pipes.

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61.         Differentiate between Newtonian and Non-Newtonian fluids.
Newtonian fluid:
The fluids which will show linear relationship between shear stress and shear strain are known as Newtonian fluids. For Newtonian fluids viscosity is constant.
Non Newtonian fluids:
The fluids which will not show linear relationship between shear stress and shear strain are known as Non-Newtonian fluids.
62.         Write the unit for surface tension coefficient.
63.         What are the two important characteristics of potential flow?
64.         Define 'mass velocity' of fluid through a channel.
65.         What is Mach number? Define the Mach number for an ideal gas.
66.         Define 'Boundary Layer'.
67.         Write Ergun's equation for pressure drop through a packed bed.
68.         Classify positive displacement pumps.
69.         Write an expression for head loss due to sudden expansion of the fluid.
70.         Write the physical significance of Froude's number.
71.         Write few industrial applications of fluidized beds.
72.         Define 'Manometric efficiency' in centrifugal pump.
73.         Write the principle of Pitot tube.
74.         Why is rotameter called an area meter?
75.         What is 'What Hammer'?
76.         What is Priming?
77.         What is the function of volute in a centrifugal pump?
78.         Write two differences between compressors and blowers.
79.         Define 'Form drag' and 'Skin drag'.
80.         Define Newtonian fluid.

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81.         What is "vapor pressure".
82.         Define kinematic viscosity.
83.         Write the unit of power in M.L.T. system.
84.         Define 'stream tube'.
85.         What is 'form drag'?
86.          State the use of Reynolds number in fluid flow.
87.         Indicate a possible velocity profile in "Turbulent flow".
88.         Define the term 'Mach number'.
89.         State Euler's equation for ideal fluid flow.
90.         Why the length of divergent section of a venturimeter is much longer than its convergent section.
91.         Define the term "Coefficient of Contraction".
92.         Write the expression for discharge through a V-notch with an included angle of 
93.         What are the types of Hot-wire anemometer used in practice?
94.         Suggest a flow meter for measuring slurry flow in a closed pipeline.
95.         Define the term "Fluidization".
96.         Name any two types of positive displacement pump.
97.         Name any three applications for continuous fluidization.
98.         Define the term "shut off head" of a centrifugal pump.
99.         Which fan produce a high static pressure rise, a backward curved fan or a forward curved fan
100.       Define the term 'Static head'.

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101.       State Bernoulli equation. Write dimensions for each term involved.
102.       Differentiate between absolute viscosity and kinematic viscosity. Write the units.
103.       Define 'Equivalent diameter' for fluid flow through ducts of noncircular diameter.
104.       Write the physical significance of Mach number.
105.       What is meant by 'skin friction'?
106.       Explain the terms maximum velocity and average velocity for a flow of fluid in a circular pipe.
107.       Write Blake-Plummer equation for packed beds.
108.       State Darcy's law.
109.       Name two types of fluidization and give two important industrial application.
110.       How will you calculate the head developed by a pump?
111.       Write any four important advantages of multistage compressors.
112.       Determine the density of air under a vacuum of 445 mm Hg at 45oC.
113.       Write the working principles of ultrasonic flow meters.
114.       What is meant by loading in a packed tower?
115.       Write a short note on positive displacement pumps.
116.       Write momentum equation for compressible flow.
117.       What is Newton's law of viscosity?
118.       State the similarity laws
119.       What is potential flow?
120.       State the type of fluid in the following cases:
(a) Rubber latex       (b) Bentonite clay

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121.       Define equivalent diameter of pipe
122.       Distinguish between form drag and skin drag
123.       Define Mach number
124.       What is the relation between maximum velocity and average velocity in laminar flow and turbulent flow
125.       Draw velocity profile for laminar flow in a circular pipe
126.       Compare and contrast venturi meter and orifice meter
127.       What is the principle of working of pitot tube?
128.       Give examples of area and head flow meters
129.       Define porosity and minimum fluidization velocity
130.       Draw the drag curves for regular solids
131.       State Ergun's equation and its application
132.       Define boundary layer
133.       What is meant by NPSH?
134.       Compare centrifugal pump with reciprocating pump
135.       List the various losses occurring in centrifugal pump
136.       Write the filed of application of various flow meters
137.       Part A (20 x 2 = 40 Marks)
138.       Differentiate between barometric pressure and absolute pressure.
139.       What is meant by pressure of a liquid column?
140.       Define the term 'Slip velocity'.

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141.       Give two important industrial applications of fluidized bed.
142.       Write the principle of Rotameter.
143.       Give the relationship between Drag coefficient and Reynolds number in a) Newton's range of operation b) Intermediate range of operation
144.       Write the physical significance of Archimedes number.
145.       Explain the term 'Darcy friction factor'.
146.       What is meant by compressible fluids? Give two examples.
147.       Write Kozeny-Carman equation for packed beds.
148.       Define the term Orifice coefficient.
149.       Define (a) Static suction lift (b) Static suction head.
150.       Give any four important criteria involved in the selection of pumps.
151.       What is meant by boundary layer thickness?
152.       Differentiate between fans and blowers.
153.       Write the continuity equation for compressible flow.
154.       What is meant by flooding in packed towers?
155.       Explain 'Cavitation' in pumps.
156.       Define the term hindered settling.
157.       Steam jet ejectors.
158.       Selection of pumps for handling of liquids.
159.       Water hammer.
160.       Net positive suction head.

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161.       What is cavitation and how it can be eliminated for a centrifugal pump?
162.       Write down the equation for flow rate through a V-notch
163.       Define the term 'Mach number'
164.        (i)  What is wall drag?
(ii) What is form drag?
165.       Differentiate between Loading and Flooding
166.       Differentiate between bubbling and particulate fluidization
167.       What is the theoretical maximum operable velocity for a fluidized bed?
168.       Consider a duct of square cross section of side 'b'. The hydraulic radius is given by
          (A) b/8          (B) b/4                   (C) b/2                   (D) b
169.       A rotameter, through which air at room temperature and atmospheric pressure is  flowing, gives a certain reading for a flow rate of 100 cc/s. If helium (Molecular weight 4) is used and the rotameter shows the same reading, the flow rate is
(A) 26 cc/s              (B) 42 cc/s              (C) 269 cc/s            (D) 325 cc/s

Comparisons - Fluid Mechanics Questions

Distinguish between compressible and incompressible fluids.

Distinguish between Newtonian and non-Newtonian fluids.

Indicate the difference between skin friction and form friction.

Differentiate between packed and fluidized beds.

Differentiate between loading and flooding velocities in a packed absorption column.

Differentiate between aggressive and particulate fluidization.

How do variable head meters differ from variable area meters for the measurement of fluid flow?

Compare the advantages and disadvantages of centrifugal pump reciprocating pump.

Distinguish between Fans and Blowers, pumps and Compressors.

Some More Questions on FLUID MECHANICS

Define 'Bulk modulus'. Write down its units.

Bulk modulus (K) = (change in pressure) / (volumetric strain)

Volumetric strain is a ratio of the change in volume to the original volume. Therefore, (change in volume) / (original volume) = (change in pressure) / (bulk modulus), i.e., -dV/V = dP/K Negative sign for dV indicates the volume decreases as pressure increases. In the limit, as dP tends to 0, K = -V dp/dV. In terms of density, K = rdp/dr.

Bulk modulus has the units of pressure; N/m2.

What is a Newtonian fluid? Give two examples.

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Fluid which obeys the Newton's law of viscosity, are said to be Newtonian fluids. Examples: water, air, kerosene.  Newton's law of viscosity, t = m du/dy

Give suitable examples for (a) Bingham plastic fluid, (b) Thixotropic fluid
Bingham plastic fluid: Tooth paste, gels, sewage sludge

Thixotropic fluid: paint

State the Pascal's law of pressure at a point in a fluid.

Pressure at a point is same in all directions. This is Pascal's law. This applies to fluid at rest
It is impossible to have gauge pressures that are as low as -20 psig. Justify this statement.
-20 psig = -20 + 14.7 = -5.3 psia. The minimum possible pressure is only 0 psia. Therefore, the   given gauge pressure is an impossible one.

Differentiate between 'steady' and 'unsteady flow' with suitable examples.

Define 'ideal fluid'. What is the value of Reynolds number for an ideal fluid?

Ideal fluid is a hypothetical fluid which is assumed to have a viscosity of zero, and incompressible.

Reynolds number of an ideal fluid is infinity.

Determine whether the velocity components given below satisfy the equation of continuity:
          u = 2x2 + zy, v = -2xy + 3y2 + 3zy, w = -1.5z2 - 2xz - 6yz are given
Where u, v and w are velocity components in the directions of x, y and z respectively.
du/dx = 4x, dv/dy = -2x + 6y + 3z                              dw/dz = -3z - 2x - 6y
du/dx + dv/dy + dw/dz = 0.

Hence, continuity equation is satisfied.

Write Bernoulli's equation. State its assumptions.
·         Flow is steady, inviscid and incompressible.
·         There is no addition of energy in between the sections considered.


1.        What are the units of kinematic viscosity?
2.        Define Newtonian fluids
3.        What are Bingham plastics?
4.        Write down the momentum balance equation
5.        Define compressible and incompressible fluids
6.        Write down the dimensionless numbers
7.        Define Nusselt number
8.        Define friction factor
9.        Write the continuity equation
10.     Define porosity
11.     What is hydraulic radius?
12.     Write down the Brinkman number
13.     How is thermal diffusivity defined?
14.     What are the limitations on the relation Cp - Cv = R?
15.     State Fick's second law of diffusion
16.     Define molar average velocity
17.     What is the effect of pressure on diffusivity?
18.     Define mass flux
19.     What is diffusion?
20.      Define Newton's law of viscosity.

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21.     What is meant by non-Newtonian fluids?
22.     Give the ranges of Reynolds number for laminar flow and turbulent flow.
23.     What is the shear stress at the centre of the pipe?
24.     State the Newton's second law of motion.
25.     Define Fourier's law of heat conduction.
26.     Write on 'Shell-energy balance'.
27.     Show that the 'Grashof number' is dimensionless.
28.     Explain the term free convection and forced convection.
29.     Define the terms isothermal and non-isothermal systems.
30.     How is thermal diffusivity defined? What are its units?
31.     Compare Fick's law of diffusion with Newton's law of viscosity.
32.     Define Stoke's law.
33.     What are the units of mass transfer coefficient?
34.     Define the term diffusion controlled chemical reaction.
35.     Define Fick's second law of diffusion.
36.     What is meant by Reynold's stress?
37.     Give equations for mass transfer rate for counter diffusion.
38.     Write the momentum balance for equations of motion.
39.     Define effectiveness of a fin.
40.     For Newtonian fluids flowing through two parallel infinite flat plates, the average velocity is __________ of maximum velocity.

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Thanks for reading -
Naitik Patel
Industrial Guide

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